The GT, a carbon-bodied mid-engine sports car powered by a production-based 3.5-liter turbocharged V6, will compete in the GT Endurance Pro Class

The biggest auto race in the world is also the biggest stage for auto makers. This past weekend, hybrid prototypes from Porsche, the luxury sports car manufacturer held by VW Group, screamed and whistled to a 1-2 victory over defending champions from Audi, also owned by VW, at the 24 Hours of Le Mans. The sibling rivalry played out over the rolling countryside of La Sarthe, about 115 miles southwest of Paris, on the most perfect weekend since old Gaul, in front of a festival crowd estimated at over a...